All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
There is nothing wrong with dealing with these stores by buying a permissible product from them, even if they sell other forbidden things, especially since these stores are in countries where this is common, and if it were to be impermissible to do so because of influencing them or for fear of strengthening them, then the Muslims there would fall into embarrassment and hardship. Furthermore, the Prophet and his companions used to deal with the Jews in Madeenah, even though they dealt in Riba. Ibn Al-'Arabi in Ahkam Al-Qur’an Said: “The correct view is that it is permissible to deal with them even though they deal in Riba and their intrusion into what Allah the Almighty has forbidden them. The evidence for that is established in the Qur’an and Sunnah.”
Allah knows best.